Tracked vehicles such as military vehicles have been in use for nearly a century. Track tension of such vehicles must be maintained at the proper level throughout operation over various terrain profiles in order to keep the track from sliding off the sprocket during a sudden maneuver or turn, as well as to prevent excessive load from being applied to the tracks, the vehicle drive train, and the vehicle suspension. Additionally, track tension has a large impact on power efficiency as an over tightened or tensioned track can lead to power loss from excess friction and accelerated wear of the track system.
Track tension is typically controlled by moving a sprocket or idler wheel that engages the track. A conventional passive mechanism for moving the sprocket or idler wheel is a track tensioner employing a grease-filled cylinder. A piston in the cylinder moves as grease is added or removed through a fitting. The piston's motion functions, in turn, to move the sprocket or idler wheel relative to the track thereby causing the sprocket or idler wheel to either extend into the track path and increase the tension of the track or to withdraw from the path of the track and decrease the tension of the track.
Often, a maintenance crew will adjust such a passive track tension on a vehicle to the highest level the system might need until the next maintenance opportunity after a mission or project, regardless of whether the resulting track tension is appropriate for optimal fuel economy, vehicle mobility or track component service life. The crew will simply tighten the track until it does not fall off during dynamic vehicle use.
Track tensioning systems have also been developed which have the ability to adjust track tension during vehicle operation and in certain designs, in response to changing terrain. However, these prior art systems are expensive and require extensive vehicle modification in order to be retroactively fitted to a vehicle. Furthermore, these known track tensioners increase the vulnerability of the vehicle to breakdown due to the addition of exposed hydraulic lines outside of the vehicle armor protection. Hence these track tensioners tend to also increase vehicle maintenance requirements. These problems have resulted in the relatively limited use of such systems on current tracked vehicles.
What is needed in the art is a dynamic or active track tensioner that is easily and economically installed on new and existing vehicles and that does not result in increased vehicle vulnerability and maintenance.